It seems that our understandings are similar. I would put it that every action we take has a reaction - reaping what we sow - and the reactions to choices made in opposition to the desire of God place more and more darkness over our hearts and minds.
Actions done to please Him take that darkness away, bit by bit, so we gain spiritual health. And yes, a little bit of evil makes more evil "go down" easier, and serving God gives us a little taste of Him, so that we become more accustomed to His service and more attracted by His goodness and mercy.
Beautifully put.